This invention is concerned with mixtures yielding thermally stable, photo-crosslinkable layers and foils based on resins which contain allyl groups and are solid at room temperature, useful for the photographic preparation of layered structures.
Light-sensitive compositions based on inert organic polymeric binding agents, thickening agents or matrices and acrylic or methacrylic compounds are known in the art from German Auslegeschriften Nos. 1,205,386, 1,200,130, and 1,915,571 and form German Offenlegungsschriften Nos. 1,906,668 and 2,149,056. These compositions are partly usable in foil form for the generation of patterns and structures. The layered structures that can be produced from these compositions have only limited thermal stability. In addition, relatively high concentrations of the photo-reactive acrylic or methacrylic compounds are necessary for producing high light sensitivity. This leads to sticky photosensitive layers which, when used in common photographic techniques with contact copies, must be exposed through protective films. Since the pattern and the photosensitive layer are not in direct contact with each other, inferior resolution results due to light diffraction.
Furthermore, thermally stable, photo-crosslinkable materials having a resin component containing allyl groups are known according to U.S. Pat. No. 3,462,267 and South-African Patent No. 05209. The materials described therein however have the common disadvantage that layers having a thickness of no greater than about 1 to 5 .mu.m have sufficient light sensitivity, but with increasing layer thicknesses the light sensitivity diminishes. It is further known from German Patent No. 2,130,904 that certain photo-cross linkable systems exhibit cross-linking speeds with layer thicknesses of more than 10 .mu.m and these make possible the preparation of layered structures with sharp contours and good insulating properties. These systems consist of a prepolymer component containing carboxylic acid allylester groups and compounds containing maleimide groups. A limiting effect for many applications of such systems is the limited thermal stability of the described prepolymer components.
It has now been found according to the present invention that surprisingly the ring-positioned allyloxy groups of triallylcyanurate prepolymers in combination with compounds containing N-maleimide groups, if exposed to actinic light, give high crosslinking speeds at layer thicknesses of more than 10 .mu.m. The light-sensitive mixtures according to this invention, yield layers and films for the photographic preparation of thermally stable layered and film structures having sharp contours and of crosslinked coatings with good insulating properties.